Method of processing photographic silver dye bleach materials

ABSTRACT

A method of processing photographic silver dye bleach materials which have been exposed imagewise is provided. The process steps are (1) silver developing, (2) dye bleaching, (3) silver bleaching and (4) fixing. The treatment baths for the process steps (2), (3) and (4), or the combined treatment baths useful for process step (3) with at least one the process steps (2) or (4) contain water-soluble tertiary phosphines as silver ligands. These phosphines effect an acceleration of the dye and silver bleaching and they are further suitable stabilizers and optionally antioxidants which yield stable treatment baths.

The conventional method of processing photographic silver bleachmaterials, such as that described for example in German Pat. Nos.1,472,811 and 1,924,723, or also in textbooks (see for example E.Mutter: "Farbenphotographie, Theorie and Praxis," Springer 1967, p. 57),comprises up to 10 steps. However, for individual steps, for examplethat of colour bleaching, the maintenance of the process conditions forlong caused difficulties. For example, in order to attain practicalresults it was necessary to maintain the temperature and the action timeof the baths very exactly. The variability and thus the limited lengthof use of individual baths, as well as the corrosiveness of the stronglyacid dye bleach bath, gave rise to further difficulties.

There has therefore been no lack of attempts to simplify the method ofprocessing and, above all, also to shorten it. These attempts haveestablished that, while maintaining certain conditions which relate bothto the material to be processed and to the composition of the treatmentbaths, it is possible to produce a useful material with the minimumnumber of the four following process steps:

(1) silver developing (developing the latent image),

(2) dye bleaching (bleaching the image dyes in relation to imagewisedeveloped silver),

(3) silver bleaching (oxidative removal of the residual silver which isnot consumed during the colour bleaching),

(4) fixing (removal of the light-sensitive silver compounds which remainat the areas where no image has been produced and which formed duringthe silver bleaching).

Washing can be performed between these steps; but it is also possible todispense with intermediate washing procedures under suitable processconditions and only to keep the final washing step. What is in effect afour-step processing method of this kind is described in GermanOffenlegungsschrift No. 2,530,469; German Offenlegungsschrift No.2,309,526 discloses that the method can be shortened and speeded upstill further by combining the silver bleaching with the fixing step.

Additional possibilities of shortening the processing method arise froma combination of steps (2) and (3), i.e. the dye bleaching and silverbleaching. German Offenlegungsschrift No. 2,448,433 discloses such aprocessing method, which, provided the final washing step is left out ofaccount, comprises only three steps, namely (1) the silver development,(2) and (3) a combined dye and silver bleaching bath, and (4) the mixingbath.

Finally German Pat. No. 735,672 teaches a silver bleach method in whicheven process steps (2), (3) and (4) have been combined in a single bath,so that the entire processing method comprises only two steps. However,in actual practice this method encounters considerable difficulties andit has therefore never been possible to develop it to final fruition.

In analogy to other processes of silver halide photography, in certainprocess steps of the silver dye bleach method so-called silver ligandsare also used, i.e. those substances which lower the concentration offree silver ions in the processing solutions by forming stable complexeswith these. In particular, the use of complexing agents, such asthiosulphate or thiocyanate ions or also for example thiourea, in thefixing process is known, wherein advantage is taken of the readysolubility of the silver complexes in question in order to remove thelight-sensitive silver compounds from the material. As regards thesilver dye bleaching processing, it has long been known to use silverligands also for process steps (2) and (3), i.e. for the dye bleachingand the silver bleaching, in order to carry out these process steps togive a result which is of practical use. Thus, for example, thiourea,thiosemicarbazide, and halide ions, such as chloride, bromide or iodideions, are used for this purpose. The ready solubility of the complexesis of secondary importance in these process steps, since the silvercomplexes do not have to be ultimately removed from the material untilthe subsequent fixing.

Under specific conditions and for special ends, small amounts of silverligands are also used in process step (1), the silver developing.Consequently, with silver dye bleach materials which contain inindividual layers iodide-free silver halide, and adjacent to these alayer of nuclei, it is possible to produce specific masking effects byusing a developer which contains a silver ligand.

The present invention is based on the observation that, when processingsilver dye bleach materials, certain tertiary phosphines can be usedwith advantage as silver ligands in process steps (2), (3) and (4), inparticular in steps (2) and (3). If they are added to the treatmentbaths, preferably in small amounts, for example from 1 to 20 g perliter, they effect a suprising intensification of the reactions, inparticular an acceleration of the dye bleaching and of the silverbleaching. Such an advantageous effect is observed both when processsteps (2) and (3) are carried out separately and when they arepreferably combined to a joint treatment (2) + (3). Further combinedtreatment baths can also be used for process steps (3) + (4) or also(2) + (3) + (4).

Accordingly, the present invention provides a method of processingphotographic silver dye bleaching materials involving the process steps

(1) silver developing,

(2) dye bleaching,

(3) silver bleaching,

(4) fixing,

it being possible to combine process step (3) with at least one of theprocess steps (2) and (4) in a single treatment step, wherein awater-soluble phosphine of the formula ##STR1## is used as silverligand, wherein W is a radical of the formula --C_(r) H_(2r) CN or--C_(r) H_(2r) NO₂, in which r is an integer from 1 to 25, a substitutedor unsubstituted aryl radical or a heterocyclic radical, X is anoptionally further substituted alkyl group and Y is a radical of theformula ##STR2## wherein n is an integer from 1 to 5, r is an integerfrom 1 to 25 and M.sup.⊕ is a cation, each of R₁, Q₁ and T₁ isindependently a hydrogen atom or an alkyl group of 1 to 4 carbon atoms,Q₁ and T₁ together with n can also form one of the radicals of theformulae ##STR3## and X and Y together are --CH₂ --CH₂ --NR₁ --CH₂ --CH₂--, wherein R₁ is a hydrogen atom or an alkyl group of 1 to 4 carbonatoms.

The water-soluble phosphine of formula (1) used as silver ligand canform with the Ag.sup.⊕ ion at least a 2:1 complex (AgL₂.sup.⊕) whosegross stability constant β₂ = [AgL₂.sup.⊕ ]/[Ag.sup.⊕ ][L]² is at least10¹³, but is preferably in the region of 10¹⁶ to 10¹⁸. The correspondingphosphonium ion has in general a pK_(a) value of less than 5, preferablyless than 3. However, this feature imposes no limitation on theperformance of the method of the invention.

The cation M.sup.⊕ can be for example H.sup.⊕, Na.sup.⊕, K.sup.β.(NH₄).sup.⊕, (amine).sup.⊕,optionally also Ca.sup.⊕⊕ or Mg.sup.⊕⊕[=M.sup.⊕ M.sup.⊕ ].

Q₁ is a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, forexample methyl, ethyl, iso-propyl, n-butyl or tert. butyl, and Q₁together with T₁ and N can also form one of the cyclic radicals ##STR4##

The substituent R₁ represents a hydrogen atom or an alkyl group of 1 to4 carbon atoms. Suitable alkyl groups are those mentioned above in thedefinition of Q₁.

T₁ is a hydrogen atom or an alkyl group of 1 to 4 carbon atoms (cf. thedefinition of Q₁) and together with Q₁ and N can also form one of thecyclic radicals ##STR5##

W is one of the radicals of the formulae --C_(r) H_(2r) --CN and --C_(r)H_(2r) --NO₂ with preferably unbranched carbon chain, wherein r is aninteger from 1 to 25, an aryl radical, in particular phenyl, which isoptionally further substituted by halogen atoms, in particular chlorineor bromine atoms by alkyl, alkoxy or sulfonic acid radicals, or W is aheterocyclic radical.

Preferred phosphines have the following formulae (2) to (6): ##STR6##wherein X and Y have the indicated meanings and W₁ is a pyridine,pyrazine or triazine radical or a radical of the formulae --CH₂ --CH₂--CN, --CH₂ --CH₂ --NO₂, ##STR7## wherein M.sup.⊕ is a cation and eachof R₁ and R₂ is independently a hydrogen atom or an alkyl group of 1 to4 carbon atoms; ##STR8## wherein W₁ and Y have the indicated meaningsand X₁ is ##STR9## or alkyl-halogen, wherein the alkyl moiety contains 1to 15 carbon atoms, M.sup.⊕ is a cation, each of R₁, R₂ and R₃independently is a hydrogen atom or an alkyl group of 1 to 4 carbonatoms, U is an alkyl group of 1 to 4 carbon atoms and n is an integerfrom 1 to 5, and X₁ and Y together can be --CH₂ --CH₂ --NR₁ --CH₂ --CH₂--, wherein R₁ has the indicated meaning; ##STR10## wherein W₁ and X₁have the indicated meanings and Y₁ is ##STR11## wherein n is an integerfrom 1 to 5, r₁ is an integer from 1 to 15 and M.sup.⊕ is a cation, andeach of R₁, Q₁ and T₁ independently is a hydrogen atom or an alkyl groupof 1 to 4 carbon atoms, Q₁ and T₁ together with N can form a radical ofthe formula ##STR12## and X₁ and Y₂ together can be --CH₂ --CH₂ --NR₁--CH₂ --CH₂ --, wherein R₁ has the indicated meaning; ##STR13## whereinW₁ and X₁ have the indicated meanings and Y₂ is ##STR14## wherein n₁ isan integer from 1 to 3, r₂ is an integer from 1 to 4 and M.sup.⊕ is acation, each of R₁, Q₁ and T₁ is independently a hydrogen atom or analkyl group of 1 to 4 carbon atoms and Q₁ and T₁ together with N canform a radical of the formula ##STR15## and X₁ and Y₂ together can be--CH₂ --CH₂ --NR₁ --CH₂ --CH₂ --, wherein R₁ has the indicated meaning;##STR16## wherein W₁ and X₁ have the indicated meanings and Y₃ is##STR17## wherein M.sup.⊕ is a cation and X₁ and Y₃ together can be--CH₂ --CH₂ --NR₁ --CH₂ --CH₂ -- wherein R₁ has the indicated meaning.

Particularly suitable phosphines are also those of the formulae##STR18## wherein Y₃ has the indicated meaning, W₂ is ##STR19## whereineach of R₁ and R₂ is independently a hydrogen atom or an alkyl group of1 to 4 carbon atoms, alkyl is an alkylene group of 1 to 4 carbon atoms,n is an integer from 1 to 5, M.sup.⊕ is a cation and halogen is inparticular a chlorine or bromine atom, and X₂ and Y₃ together can be--CH₂ --CH₂ --NR₁ --CH₂ --CH₂ --, wherein R₁ has the indicated meaning,and phosphines of the formula ##STR20## wherein Y₃ has the indicatedmeaning, W₃ is --CH₂ --CH₂ --CN or ##STR21## wherein M.sup.⊕ is acation, U is an alkyl group of 1 to 4 carbon atoms and n₁ is an integerfrom 1 to 3 and k is an integer from 2 to 4, R₁ and R₂ have theindicated meanings and X₃ and Y₃ together can be --CH₂)₂ --N(CH₃)(CH₂)₂--.

Particularly useful phosphines are also those of the formula ##STR22##wherein W₃ and Y₃ have the indicated meanings and X₄ is ##STR23##wherein M.sup.⊕ is cation and X₄ and X₃ together can be ##STR24## orphosphines of the formula ##STR25## wherein W₃ has the indicatedmeaning, Y₄ is --(CH₂)₂ --SO₃.sup.⊖ M.sup.⊕, --CH₂ N(C₂ H₅)₂, --(CH₂)₃--SO₃.sup.⊖ M.sup.⊕, --(CH₂)₄ --SO₃ .sup.⊖ M.sup.⊕ or --(CH₂)₂ --O--CH₃,X₅ --CH₂ --CH₂ CN or --(CH₂)₂ --O--CH₃ and M.sup.⊕ is a cation and X₅and Y₄ together can be ##STR26##

A number of the phosphines of the formulae (1) to (5) are known andthose of the formulae (6) to (10) are new. The phosphines can beobtained by methods which are known per se. Suitable methods ofobtaining them are described for example by Kosolapoff-Maier in "OrganicPhosphorus Compounds," Vol. 1, Chapter 1 (L. Maier), J. Wiley, New York,1972. Preferred methods are for example the reaction of alkali oralkaline earth alkylphosphides with alkyl halides or the alkylation oftertiary phosphines to give tetra-alkylphosphonium salts and subsequentdealkylation. In this way it is possible to obtain tertiary phosphineswith two or three different substituents. Details of this method are tobe found in the manufacturing examples. The following phosphines andalkylating agents can be used for example to obtain the phosphines ofthe formula (1):

Phosphines

tris-(2-cyanoethyl)-phosphine, bis-(2-cyanoethyl)-phosphine,(2-cyanoethyl)-phosphine, bis-(2-cyanoethyl)-phenylphosphine,(2-cyanoethyl)-phenyl-phosphine, (2-cyanoethyl)-diphenyl-phosphine,phenylphosphine, diphenylphosphine, tris-(hydroxymethyl)-phosphine,(2-methoxyethyl)-phosphine, bis-(2-methoxyethyl)-phosphine,bis-(2-cyanoethyl)-(2-methoxyethyl)-phosphine,bis-(hydroxymethyl)-phosphine,bis-(2-cyanoethyl)-(hydroxymethyl)-phosphine,bis-(hydroxymethyl)-2-cyanoethyl-phosphine,2-cyanoethyl-hydroxymethyl-phenylphosphine.

Alkylating agents

methyl vinyl sulphone, acrylonitrile, acrylic acid, methyl acrylate,ethyl acrylate, acrylic amide, methyl vinyl ether,2-chloroethanesulphonic acid, 2-bromoethanesulphonic acid,2-iodoethanesulphonic acid, 3-chloro-1-propanesulphonic acid,3-bromo-1-propanesulphonic acid, 3-iodo-1-propanesulphonic acid,4-chloro-1-butanesulphonic acid, 4-bromo-1-butanesulphonic acid,4-iodo-1-butanesulphonic acid, propane sultone, butane sultone,3-methylpropane sultone, 1-chloro-2-methoxyethane,1-bromo-2-methoxyethane, 1-iodo-2-methoxyethane,(2-bromoethyl)-methylsulphone, (2-chloroethyl)-methylsulphone,(2-chloroethoxy)-1-methoxyethane, (2-bromoethoxy)-1-methoxyethane,(2-iodoethoxy)-1-methoxyethane, (2-iodoethyl)-methylsulphone,bis-N,N-(2-chloroethyl)-N-methylamine,bis-N,N-(2-chloroethyl)-N-ethylamine,bis-N,N-(2-chloroethyl)-N-propylamine,bis-N,N-(2-chloroethyl)-N-isopropylamine,bis-N,N-(2-chloroethyl)-N-isopropylamine,bis-N,N-(2-chloroethyl)-N-butylamine, bis-N,N-(2-chloroethyl)-N-sec.butylamine, bis-N,N-(2-chloroethyl)-N-isobutylamine,bis-N,N-(2-chloroethyl)-N-tert. butylamine,N-(2-chloroethyl)-N,N-dimethylamine, N-(2-chloroethyl)-N,N-diethylamine,N-(3-chloro-1-propyl)-N,N-dimethylamine,N-(3-chloro-1-propyl)-N,N-diethylamine,N-(4-chloro-1-butyl)-N,N-dimethylamine,N-(4-chloro-1-butyl)-N,N-diethylamine, N-(2-chloroethyl)-pyrrolidine,N-(3-chloro-1-propyl)-pyrrolidine, N-(4-chloro-1-butyl)-pyrrolidine,N-(2-chloroethyl)-piperidine, N-(3-chloro-1-propyl)-piperidine,N-(4-chloro-1-butyl)-piperidine, N-(2-chloroethyl)-morpholine,N-(3-chloropropyl)-morpholine, N-(4-chlorobutyl)-morpholine.

The sulphonic acids are ordinarily used in the form of their alkalimetal salts.

A number of representative phosphines which can be used in theprocessing method of the present invention are listed herein below:##STR27##

The accelerating action of the phosphines mentioned above is observedboth when they used as sole ligands and when they are used together withthe ligands normally employed, such as thiocyanides, thiourea,water-soluble halides (for example chloride, bromide or iodide). Theyeffect a desirable shortening of the treatment time and in certain casesin which for different reasons the bleaching of the dyes or of thesilver is incomplete, they bring the reaction to completion - somethingwhich cannot be accomplished with the conventional ligands alone.

The use of the cited tertiary phosphines proves particularlyadvantageous in dye bleach baths which, in addition to a strong acid anda bleaching catalyst, contain as ligand a water-soluble iodide and, toprotect the iodide, an antioxidant, for example a reductone (GermanOffenlegungsschrift No. 1,924,723) or a mercaptan, such as thioglycerolor mercaptobutyric acid (German Offenlegungsschriften Nos. 2,258,076 and2,423,814). The addition of a phosphine of the indicated kind does notonly have an accelerating action in this case, but also a stabilizingand antioxidizing action. It is particularly easy to dispense with thewater-soluble iodides in such baths and to use the phosphine as soleligand.

A further important use of these phosphines is indicated in a processsuch as that described in German Offenlegungsschrift No. 2,448,433,where the dye and silver bleaching are combined in a single treatmentbath with a preparation which contains a strong acid, a water-solubleiodide, a water-soluble oxidant, an antioxidant and a large amount ofcatalyst, preferably between 0.5 and 5 g/liter. In such a process theproperty of the phosphines of speeding up both the dye bleaching and thesilver bleaching is utilised. Preparations without an antioxidant canalso be used very successfully.

Furthermore, significant advantages accrue from the two-bath processwhich has long been known from German Pat. No. 735,672, in which dyebleaching, silver bleaching and fixing are combined in a singletreatment bath, by using the tertiary phosphines of this invention assilver ligands. The few ligands hitherto known to be useful for thisprocess have for various reasons so far made it difficult to carry outin actual practice this essentially advantageous process. Thus, forexample, thiourea and its derivatives are corrosive and poisonous andare therefore also ecologically harmful; and the thiocyanide alsoproposed proves to be unstable and undesirably limits the durability ofthe baths. By comparison, the phosphines of the present inventionpossess not only the already mentioned accelerating action, but alsoyield stable baths. In addition, a number of the most suitable tertiaryphosphines are completely non-poisonous.

German Offenlegungsschrift No. 2,530,469 proposes silver bleach bathswhich contain a strong acid, a water-soluble iodide, a water-solubleorganic oxidant, a diazine in an amount of 0.5 to 5 g/l and anantioxidant. Compared with known silver bleach baths, such baths havethe advantage that they contain neither heavy metals nor theecologically equally harmful ferricyanide ion. It has been observed thatthe phosphines of the present invention also exert an accelerating andstabilising action in such baths. As in the dye bleach baths mentionedabove, the iodide ion can also be replaced here completely by aphosphine.

A further use of the proposed phosphines comprises bleach fixing baths,for example those which have been proposed for silver dye bleachmaterials in German Offenlegungsschrift No. 2,309,526. Such bathscontain a water-soluble oxidant, for example the sodium salt of2,4-dinitrobenzenesulphonic acid, and thiourea as silver ligand. The pHis kept at a maximum value of 1 by a strong acid, such as sulphuricacid. It has been observed that the phosphines of the present inventionalso exhibit an accelerating action in such baths.

A particularly advantageous use of the phosphines of this inventionresides in the production of masked positive coloured images by means ofthe silver dye bleach process, in which a photographic material is usedwhich contains, in each of at least two layers, a dye which can bebleached imagewise and whose absorption maximum corresponds to one ofthe primary colours red, green and blue, with a silver halide emulsionlayer sensitive to a particular spectral region being assigned to eachdye, and in this material,

(a) a silver halide emulsion layer consisting at least partially ofsilver iodide is assigned to the dye whose undersired parasitic colourdensity is to be compensated,

(b) in a further layer, at least a second dye whose main colour densitycorresponds to a parasitic colour density, requiring compensation, ofthe first dye, and a silver halide emulsion which contains no iodideions are present,

(c) a further layer, which is adjacent to the layer containing thesecond dye, contains colloidal nuclei which are capable of depositingmetallic silver from soluble silver complexes,

(d) a separating layer is present between the layer containing thenuclei and the dye layer the parasitic colour density of which is to becompensated, and the silver developing bath with which the material istreated contains a ligand which is able to produce water-soluble silvercomplexes which are capable of diffusion.

The following Examples 1 to 9 relate to the production of new phosphinesand Examples 10 to 15 to the use of the inventive phosphines as silverligands.

EXAMPLE 1 Bis-(β-cyanoethyl)-sulphoethylphosphine (formula 101)Phosphonium salt of tris-(2-cyanoethyl)-2-ethylsulphonic acid

19.3 g (0.1 mole) of tris-(2-cyanoethyl)-phosphine, 21.1 g (0.1 mole) ofthe sodium salt of ethanesulphonic acid and 120 ml of ethylene glycolmonomethyl ether are refluxed for 40 hours. The mixture is cooled in iceand the precipitated solid is collected by filtration, washed with asmall amount of ethylene glycol monomethyl ether and finally dried invacuo at 60° C.

Yield: 20 g (66.4% of theory).

Melting point: 253°-258° C. (with decomposition).

Bis-(β-cyanoethyl)-2-sulphoethylphosphine

1.5 g of sodium metal (0.0652 mole) are dissolved in 60 ml of absolutemethanol. Then 20 g of the above phosphonium salt (0.0664 mole) and 20ml of absolute methanol are added. The mixture is refluxed for 2 hoursand then cooled, whereupon a white crystalline product precipitates. Thebatch is filtered and then 120 ml of absolute toluene are added to thefiltrate, whereupon further crystals precipitate. The combinedcrystalline product is dried in vacuo at 60° C.

Yield: 11.7 g (66.4% of theory).

Melting point: 119°-124° C.; content (iodine titre) : 89%.

EXAMPLE 2 Bis-(β-cyanoethyl-3-sulphopropylphosphine, sodium salt(formula 102)

Starting material: tris-(β-cyanoethyl)-phosphine

Manufacture by the method of W. J. Vullo, Ind. Eng. Chem. Prod. Res.Dev. 5, 346 [1966]

Phosphonium salt of tris-(β-cyanoethyl)-3-propylsulphonic acid

15.4 g (0.08 mole) of tris-(β-cyanoethyl)-phosphine and 46 ml of tolueneare refluxed for 30 minutes. After addition of 9.84 g (0.08 mole) ofpropanesultone, the mixture is refluxed for 3 hours and then cooled to20° C. The precipitated solid is collected by suction filtration anddried in vacuo at 60° C.

Yield: 24.4 g (97.5% of theory)

Melting point: 257°-260° C. (with decomposition).

Bis-(β-cyanoethyl)-3-sulphopropylphosphine (sodium salt)

24.4 g of the above intermediate are dissolved, under nitrogen, in 100ml of absolute methanol and 1.85 g (0.08 mole) of sodium methylate areadded to the solution. The mixture is refluxed for 2 hours and thencooled to 20° C. Upon onset of crystallisation, 120 ml of ethyl etherare added dropwise and the suspension is further stirred for 30 minutes.The precipitated solid is collected by suction filtration, washed with80 ml of ether and dried in vacuo at 60° C.

Yield: 22.9 g (100%, referred to the intermediate).

Melting point: 125°-130° C. (with decomposition).

Content (iodine titre): 71 to 72%.

EXAMPLE 3 Bis-(β-cyanoethyl)-4-sulpho-1-butylphosphine (formula 103)Bis-(β-cyanoethyl)-4-sulpho-1-butylphosphonium salt

19.3 g (0.1 mole) of tris-(β-cyanoethyl)-phosphine, 13.6 g (0.1 mole) ofbutane sultone, 1.5 g (0.01 mole) of sodium iodide and 100 ml ofdimethyl formamide are refluxed for 20 hours. The mixture is cooled to5° C. and precipitated solid is separated, washed with acetone and driedat 60° C. in vacuo.

Yield: 23.5 g (71.4% of theory).

Melting point: 284°-285° C. (with decomposition).

Bis-(β-cyanoethyl)-4-sulpho-1-butylphosphine

16.5 g (0.05 mole) of the above intermediate are added, under nitrogen,to a solution of 1.15 g (0.0 mole) of sodium in 60 ml of absolutemethanol. The mixture is refluxed for 5 hours and then cooled to 5° C.Then 150 ml of isopropanol are added and the suspension is furtherstirred for 30 minutes. The precipitated solid is filtered off withsuction, washed with 150 ml of toluene and dried in vacuo at 60° C.

Yield: 13.3 g (89% of theory).

Melting point: 134°-139° C.

Content (iodine titre): 92%.

EXAMPLE 4 Bis-(β-cyanotheyl)-2-methoxyethylphosphine (formula 104)Tris-(β-cyanoethyl)-2-methoxyethyl-phosphonium iodide

135.2 g (0.7 mole) of tris-(2-cyanoethyl)-phosphine are dissolved, undernitrogen, in 500 ml of boiling acetonitrile and then 130.2 g (0.7 mole)of 1-iodo-2-methoxyethane are added. The mixture is refluxed for 12hours. After rapid filtration of the hot solution and cooling, thereaction product crystallises out and is collected by suction filtrationand dried in vacuo at 60° C.

Yield: 205.8 g (77.5% of theory).

Melting point: 170°-171° C.

Bis-(β-cyanoethyl)-2-methoxyethylphosphine

1.55 g of sodium are dissolved in 100 ml of absolute methanol under anatmosphere of argon and then 26 g (0.0685 mole) oftris-(β-cyanoethyl)-2-methoxyethyl-phosphonium iodide are added to thissolution. The solution is refluxed for 4 hours. After the mixture hasbeen poured into water, extraction is performed with three 40 mlportions of chloroform. The chloroform solution is dried over magnesiumsulphate, the solvent is evaporated and the oily residue distilled in ahigh vacuum.

Yield: 9.65 g (71% of theory).

Boiling point: 146°-147° C. (0.026 mbar).

EXAMPLE 5 Bis-(2-methoxyethyl)-β-cyanoethylphosphine (formula 106)Bis-(β-cyanoethyl)-2-bis-(2-methoxyethyl-phosphonium iodide

This product is obtained in similar manner totris-(β-cyanoethyl)-2-methoxyethyl-phosphonium ioxide (Example 4) byalkylating bis-(2-cyanoethyl)-2-methoxyethylphosphine with1-iodo-2-methoxyethane.

Yield: 96% of theory.

Melting point: 103°-106° C.

Bis-(2-methoxyethyl)-(β-cyanoethyl)-phosphine

This phosphine is obtained in similar manner tobis-(2-cyanoethyl)-2-methoxyethylphosphine (Example 4) frombis-(2-cyanoethyl)-bis-(2-methoxyethyl)-phosphonium iodide.

Yield: 10% of theory.

Boiling point: 103°-104° C. (0.09 Torr).

Example 6 β-Cyanoethyl-phenyl-3-sulphopropylphosphine (formula 108)

Starting product: phenylphosphine

F. Pass & H. Schindlbauer, Monatshefte Chemie 90 148 [1959]

Bis-(β-cyanoethyl)-phenylphosphine

M.M. Rauhut et al., J. Am. Chem. Soc. 81,1106 [1959]

Phosphonium salt of bis-(β-cyanoethyl)-phenyl-3-propyl-1-sulphonic acid

8.5 g (0.039 mole) of bis-(β-cyanoethyl)-phenylphosphine, 20 ml ofabsolute acetonitrile and 4.76 g (0.039 mole) of propanesultone arerefluxed for 16 hours under a nitrogen atmosphere. After evaporation ofthe solvent, the solid residue is heated for 2 hours with ethyl and thenfiltered off with suction and dried in vacuo to yield 12 g (79%) of thephosphonium salt. The NMR spectrum is in accord with the expectedformula.

(β-Cyanoethyl)-phenyl-3-sulphopropylphosphine (sodium salt)

0.7 g of sodium are dissolved in 40 ml of absolute methanol in anatmosphere of nitrogen. The 12 g of the phosphonium salt ofbis-(2-cyanoethyl)-phenyl-(3-propyl-1-sulphonic acid are added and themixture is refluxed for 12 hours. The solution is cooled and poured intowater. The insoluble constituent is filtered off and the water iscompletely evaporated. The residue is taken up in ether, filtered offwith suction, washed once more with ether and dried in vacuo at 70° C.

Yield: 8.5 g (92% of theory).

Melting point: 120° C. (with decomposition).

The NMR spectrum (in dimethyl sulphoxide) accords with the expectedformula.

EXAMPLE 7 β-Cyanoethyl-2-methoxyethylphenylphosphine (formula 110)Bis-(β-cyanoethyl-2-methoxyethyl-phenylphosphonium iodide

8.5 g (0.04 mole) of bis-(β-cyanoethyl)-phenylphosphine are dissolved in50 ml of absolute acetonitrile in a nitrogen atmosphere. Then 7.71 g(0.04 mole) of 1-iodo-2-methoxyethane are added and the mixture isrefluxed for 12 hours. The solvent is distilled off to yield 13.2 g (82%of theory) of the product in the form of a solid, glassy substance.

β-Cyanoethyl-2-methoxyethyl-phenylphosphine

The product is obtained frombis-(2-cyanoethyl)-2-methoxyethyl-phenylphosphonium iodide by reactionwith sodium methylate in absolute methanol, in the same way as the endproduct of Manufacturing Example 4.

Yield: 53% of theory.

Boiling point: 125° C. (0.13 mbar).

EXAMPLE 8 Bis-(2-methoxyethyl)-phenylphosphine (formula 111)

39.2 g (1.7 mole) of sodium are finely dispersed in 500 ml of boilingtoluene, using a vibrator, in an argon atmosphere. Without cooling, asolution of 71.6 g (0.4 mole) of phenyl-dichlorophosphine in 150 ml ofdry toluene is slowly added dropwise. The mixture is refluxed for afurther 5 hours. Then 85 g (0.9 mole) of 1-chloro-2-methoxyethane areslowly added dropwise, in the course of which the mixture reactsvigorously. The batch is thereafter refluxed for a further 2 hours.After the batch has cooled, 150 ml of water are added dropwise and thephases are separated. The aqueous solution is extracted a second timewith 50 ml of toluene and both toluene solutions are combined. Afterdrying the combined extracts over magnesium sulphate the toluene isevaporated and the residue is distilled in a high vacuum in anatmosphere of argon.

Boiling point: 85°-90° C. (0.39 bar).

Yield: 30.9 g (34% of theory).

EXAMPLE 9 N-Methyl-p-phenyl-perhydro-1,4-azaphosphorane (formula 112)

A solution of phenylmagnesium bromide is prepared from 2.7 g (0.11 mole)of magnesium and 15.7 g of bromobenzene in a total amount of 110 ml ofdry tetrahydrofurane. To the cooled solution are added dropwise 5.5 g(0.05 mole) of phenylphosphine in 40 ml of absolute benzene. The mixtureis refluxed for 2 hours and cooled again to 30° C. Then 7.8 g ofmethyl-bis(2-chloroethyl)-amine in 40 ml of dry benzene are addeddropwise. The batch is subsequently stirred for 12 hours at roomtemperature and then refluxed once more for 2 hours. After the batch hascooled, 100 ml of water are added and the phases are separated. Afterrepeated extraction of the aqueous phase with benzene, the solutions arecombined and the solvent is evaporated. The oily residue is distilled invacuo in an argon atmosphere.

Boiling point: 146° C. (11 mbar).

Yield: 3.2 g.

Control of the constitution by NMR, IR and mass spectra.

EXAMPLE 10

A photographic material for the silver dye bleach process is produced ona pigmented cellulose acetate carrier using the cyan image dye of theformula ##STR28## in the red-sensitised bottom layer, the magenta dye ofthe formula ##STR29## in a green-sensitised layer above this, and theyellow dye of the formula in a blue-sensitive layer above the magentalayer.

The photographic material used is made up as follows (compare GermanOffenlegungsschriften Nos. 2,036,918 and 2,132,836):

gelatine protective layer

blue-sensitive iodide-free AgBr emulsion

yellow dyestuff (116) + blue-sensitive, iodide-free AgBr emulsion

yellow filter: yellow Ag hydrosol (40 mg/m²)

green-sensitive AgBr/AgI emulsion

magenta dyestuff (115) + green-sensitive AgBr/AgI emulsion

intermediate layer (gelatine)

cyan dyestuff (114) + red-sensitive AgBr/AgI emulsion

red-sensitive AgBr/AgI emulsion

cellulose triacetate carrier, opaque white

backing layer, gelatine

The emulsion layers containing iodide contain crystals with 2.6 mol % ofsilver iodide and 97.4 mol % of silver bromide. The image dyes are usedin such a concentration that the reflection density of each is 2.0. Thetotal silver content of the material is 2.0 g/m², and the overallthickness of the photographic layers is 22μ.

A colour transparency is copied onto this material in an enlarger. Theexposed material is processed in accordance with the followinginstructions. The processing temperature is 24° C.

    ______________________________________                                        1. Silver developer bath                                                                            3       minutes                                         sodium polyphosphate  1       g/l                                             potassium hydroxide (85%)                                                                           27      g/l                                             boric acid            16      g/l                                             potassium metabisulphite                                                                            18      g/l                                             1-phenyl-3-pyrazolidone                                                                             0.3     g/l                                             hydroquinone          10      g/l                                             ascorbic acid         10      g/l                                             benzotriazole         0.3     g/l                                             potassium bromide     2       g/l                                             2. Bleach bath        5       minutes                                         sulphamic acid        140     g/l                                             sodium-3-nitrobenzenesulphonate                                                                     6       g/l                                             4-mercaptobutyric acid                                                                              1       ml/l                                            potassium iodide      6       g/l                                             2,3,6-trimethylquinoxaline                                                                          2       g/l                                             3. Washing            2       minutes                                         4. Fixing bath        4       minutes                                         ammonium thiosulphate 250     g/l                                             potassium metabisulphite                                                                            50      g/l                                             potassium hydroxide (85%)                                                                           20      g/l                                             5. Washing            6       minutes                                         ______________________________________                                    

The positive reproduction of the original is obtained after a totalprocessing time of 20 minutes.

By using instead of the above bleaching bath one of the composition:

    ______________________________________                                        sulphamic acid           140     g/l                                          sodium m-nitrobenzenesulphonate                                                                        6       g/l                                          2,3,6-trimethylquinoxaline                                                                             2       g/l                                          potassium iodide         6       g/l                                          4-mercaptobutyric acid   1       ml/l                                         bis-(β-cyanoethyl)-sulphoethylphosphine (101)                                                     2.5     g/l                                          (sodium salt)                                                                 ______________________________________                                    

the same result is obtained and the bleaching time is reduced to 3minutes.

EXAMPLE 11

The same photographic material is used as in Example 10, but using asilver developing bath of the following composition:

    ______________________________________                                        sodium polyphosphate     1       g/l                                          potassium hydroxide (85%)                                                                              27      g/l                                          boric acid               21      g/l                                          potassium metabisulphite 18      g/l                                          1-phenyl-3-pyrazolidone  0.3     g/l                                          hydroquinone             5       g/l                                          ascorbic acid            10      g/l                                          benztriazole             0.6     g/l                                          potassium bromide        2       g/l                                          sodium thiosulphate      1.5     g/l                                          ______________________________________                                    

Baths of the same composition as that described in Example 10 are usedfor the other baths. It is observed that in a bath without the additionof tertiary phosphine the silver is no longer completely bleached out,but leaves a grey fog on the finished processed image.

If, however, 2.5 g/l of bis-(β-cyanoethyl)-sulphopropylphosphine (102)are added to the bleaching bath, then the silver is completely bleachedout and the bleaching time is simultaneously reduced. The masking affectobtained by adding sodium thiosulphate to the developer is fullyretained and, compared with the images prepared in accordance withExample 10, brilliant saturated blue shades and also at the same timesaturated yellow and green shades are obtained. The same result isobtained by using 9 g/l of diphenyl-sulphopropylphosphine instead ofbis-(β-cyanoethyl)-sulphopropylphosphine.

EXAMPLE 12

A colour transparency is copied in an enlarger onto the materialdescribed in Example 10. Processing is effected using a bath sequence inwhich the silver developing, dye bleaching, silver bleaching and fixingare carried out in separate successive treatments:

    ______________________________________                                        1. Silver developing: 6 minutes                                               sodium polyphosphate     1        g/l                                         sodium sulphite, anhydrous                                                                             50       g/l                                         hydroquinone             5        g/l                                         sodium metaborate        15       g/l                                         1-phenyl-3-pyrazolidone  0.3      g/l                                         potassium bromide        3        g/l                                         benzotriazole.           0.2      g/l                                         2. Washing: 5 minutes                                                         3. Dye bleaching: 7 minutes                                                   water                    800      ml                                          sulphuric acid (95%)     14       ml                                          ascorbic acid            1        g                                           potassium iodide         30       g                                           2,3-dimethyl-5-amino-6-methoxy-                                               quinoxaline              0.08     g                                           bulked with water to     1000     ml                                          4. Washing: 3 minutes                                                         5. Silver bleaching: 3 minutes                                                water                    800      ml                                          sulphuric acid (96%)     20       ml                                          2,4-dinitrobenzenesulphonic acid,                                                                      10       g                                           sodium salt                                                                   ascorbic acid            1        g                                           potassium iodide         6        g                                           ammonium chloride        20       g                                           2,3,6-trimethylquinoxaline                                                                             0.5      g                                           bulked with water to     1000     ml                                          6. Washing: 3 minutes                                                         7. Fixing: 7 minutes                                                          ammonium thiosulphate    200      g/l                                         sodium sulphite, anhydrous                                                                             20       g/l                                         8. Washing: 8 minutes                                                         ______________________________________                                    

The above silver bleaching bath has the advantage of containing neitherheavy metal nor cyanide ions, both of which cause effluent pollution.The bleaching time can be reduced to 1 minute by addingbis-(β-cyanoethyl)-sulphopropylphosphine (102) to this bleaching bath inan amount of 5 g/l. In both cases a true coloured positive copy of theoriginal is obtained. Instead ofbis-(β-cyanoethyl)-sulphopropylphosphine (102) it is also possible touse with similar effect bis-(β-cyanoethyl)sulphoethylphosphine (101) orcyanoethyl-phenyl-sulphopropylphosphine (108) or the compound of theformula (112).

EXAMPLE 13

A silver dye bleach material suitable for rapid processing in automaticself-protrait machines is prepared as follows:

Three colour layers are applied superimposed to a paper carrier which islaminated on both sides with polyethylene. The material contains in thebottom layer the cyan dye of the formula ##STR30## in thegreen-sensitive layer above it the magenta image dye of the formula(115) and in the top blue-sensitive layer the yellow image dye of theformula (116).

The image dyes are incorporated in a reflectance density of D = 2.0. Thecolour layers containing a total of 0.8 Ag/m² are separated by gelatinelayers, the total thickness being 15μ.

This material is exposed by flashlight in a conventional automaticself-portrait machine and thereafter developed in the processing part ofthe machine. Fourteen tanks each containing 2.5 liters are evailable forholding the solutions. The immersion time per tank, including transport,is 20 seconds. The exposed material passes through the following bathsat a bath temperature of 35° C:

    ______________________________________                                        Twice, silver developing bath                                                 Composition                                                                   sodium polyphosphate                                                                            1       g/l                                                 sodium sulphite, anhydrous                                                                      60      g/l                                                 hydroquinone      10      g/l                                                 sodium metaborate 20      g/l                                                 sodium hydroxide  3       g/l                                                 1-phenyl-3-pyrazolidone                                                                         0.4     g/l                                                 potassium bromide 1.5     g/l                                                 benzotriazole     0.2     g/l                                                 2,3-bis-(hydroxymethyl)-6,7-                                                  dimethoxy-quinoxaline                                                                           0.2     g/l                                                 Passage time                     40 seconds                                   Twice, dye bleach bath                                                        Composition                                                                   sulphuric acid (96%)                                                                            20      ml/l                                                sodium hypophosphite                                                                            2       g/l                                                 potassium iodide  20      g/l                                                 2,3-bis-(hydroxymethyl-6,7-                                                   dimethoxy-quinoxaline                                                                           80      mg/l                                                Passage time                     40 seconds                                   Twice, bleach-fixing bath                                                     Composition                                                                   sulphuric acid (96%)                                                                            20      ml/l                                                sodium salt of 2,4-dinitrobenzene-                                            sulphonic acid    70      g/l                                                 thiourea          80      g/l                                                 Passage time                     40 seconds                                   3 times, silver halide fixing bath                                            Composition                                                                   ammonium thiosulphate, 98/100                                                                   150     g/l                                                 sodium sulphate, anhydrous                                                                      30      g/l                                                 sodium bisulphite 10      g/l                                                 Passage time                     60 seconds                                   5 times, washing bath                                                         Passage time                     100 seconds                                  Total processing time            280 seconds                                                                   (= 4 minutes                                                                  40 seconds)                                  ______________________________________                                    

By adding 5 g/l of bis-(β-cyanoethyl)-methoxyethylphosphine (104) or ofbis-(β-cyanoethyl)-sulphopropylphosphine (102) both to the dye bleachbath and to the bleach fixing bath, the treatment time in both baths canbe reduced by half and the result will in other respects be the same.

EXAMPLE 14

This Example illustrates the use of the phosphines of the presentinvention in a two-bath process, in which the process steps dyebleaching (2), silver bleaching (3) and fixing (4) are combined in asingle treatment bath.

In an enlarger, the copy of a colour transparency is prepared on thephotographic material used in Example 13 with 3 layers which contain dyeand emulsion and each of which is separated by an intermediate layer ofgelatine. The exposed material is processed in the following bathsequence at a temperature of 22° C.:

    ______________________________________                                        sodium polyphosphate     1      g/l                                           sodium sulphite, anhydrous                                                                             50     g/l                                           hydroquinone             5      g/l                                           sodium metaborate        15     g/l                                           1-phenyl-3-pyrazolidone  0.3    g/l                                           potassium bromide        3      g/l                                           benzotriazole            0.2    g/l                                           2. Combined dye-silver-bleach-fixing bath                                     Bis-(β-cyanoethyl)-methoxyethylphosphine                                   (10 × 4)         20     g/l                                           2,3-dimethyl-6-methoxyquinoxaline                                                                      3      g/l                                           sodium 3-nitrobenzenesulphonate                                                                        5      g/l                                           sulphuric acid (96%)     30     ml/l                                          ______________________________________                                    

After a two minute treatment in this bath, a finished, bleached andfixed positive image of the original is obtained, which only needs to bewashed. Instead of the phosphine used in the bleaching bath, it is alsopossible to use the same amount ofbis-(β-cyanoethyl)-sulphoethylphosphine (101) orphenyl-(β-cyanoethyl)-sulphopropylphosphine (108) to obtain the sameeffect. The treatment time in the combined bleaching and fixing bath caneven be reduced to one minute by using a bath of the followingcomposition:

    ______________________________________                                        bis-(β-cyanoethyl)-sulphopropylphosphine (102)                                                     33 g/l                                              potassium iodide          10 g/l                                              2,3,6-trimethylquinoxaline                                                                              3 g/l                                               sodium 3-nitrobenzenesulphonate                                                                         5 g/l                                               sulphuric acid (96%)      30 g/l                                              ______________________________________                                    

EXAMPLE 15

The procedure described in Example 10 is repeated, but instead of thebleaching bath (2), a bath of the following composition is used:

    ______________________________________                                        sulphamic acid            140 g/l                                             sodium 3-nitrobenzenesulphonate                                                                         6 g/l                                               2,3,6-trimethylquinoxaline                                                                              2 g/l                                               potassium iodide          6 g/l                                               bis-(β-cyanoethyl)-sulphoethylphosphine,                                 sodium salt (formula 101).                                                                              2.5 g/l                                             ______________________________________                                    

With this composition the bleaching time can be reduced to 3 minutes.Equally good results are obtained with the phosphines of Examples 2 to9.

We claim:
 1. A method of processing imagewise exposed photographicsilver dye bleach materials involving the process steps(1) silverdeveloping, (2) dye bleaching, (3) silver bleaching, (4) fixing,it beingpossible to combine process step (3) with at least one of the processsteps (2) and (4) in a single treatment step, which method comprisesusing in at least one of the steps (2), (3) or (4) a water-solubletertiary phosphine of the formula ##STR31## is used as silver ligand,wherein W is a radical of the formula --C_(r) H_(2r) CN or --C₂ H_(2r)NO₂, in whichr is an integer from 1 to 25, a pyridine, pyrazine ortriazine radical or a radical of the formulae ##STR32## wherein M.sup.⊕is a cation and each of R₁ and R₂ is independently a hydrogen atom or analkyl group of 1 to 4 carbon atoms, X is ##STR33## or alkyl-halogen,wherein the alkyl moiety contains 1 to 15 carbon atoms, M.sup.⊕ is acation, each of R₃, R₄ and R₅ is independently a hydrogen atom or analkyl group of 1 to 4 carbon atoms, U is an alkyl group of 1 to 4 carbonatoms and n is an integer from 1 to 5, and Y is a radical of the formula##STR34## wherein n is an integer from 2 to 5, r is an integer of 1 to25 and M.sup.⊕ is a cation, each of R₁, Q₁ and T₁ is independently ahydrogen atom or an alkyl group of 1 to 4 carbon atoms, Q₁ and T₁together with the nitrogen atom to which they are attached can also formone of the radicals of the formulae ##STR35## and X and Y together are--CH₂ --CH₂ --NR₁ --CH₂ --CH₂, wherein R₁ has the indicated meaning. 2.A method according to claim 1 wherein the silver ligand is a phosphineof the formula ##STR36## wherein W₁ and X₁ are as defined in claim 3 andY₁ is ##STR37## wherein n is an integer from 2 to 4, r₁ is an integerfrom 1 to 15 and M.sup.⊕ is a cation and each of R₁, Q₁ and T₁independently represents a hydrogen atom or an alkyl group of 1 to 4carbon atoms, Q₁ and T₁ together can be a radical of the formula##STR38## and X₁ and Y₁ together with the nitrogen atom to which theyare attached can be --CH₂ --CH₂ --NR₁ --CH₂ --CH₂ --, wherein R₁ has theindicated meaning.
 3. A method according to claim 1, wherein the silverligand is a phosphine of the formula ##STR39## wherein W₁ and X₁ are asdefined in claim 1 and Y₂ is ##STR40## wherein n₁ is an integer from 1to 3, r₂ is an integer from 1 to 4 and M.sup.⊕ is a cation, each of R₁,Q₁ and T₁ independently is a hydrogen atom or an alkyl group of 1 to 4carbon atoms, Q₁ and T₁ together with the nitrogen atom to which theyare attached can be a radical of the formula ##STR41## and X₁ and Y₂together can be --CH₂ --CH₂ --NR₁ --CH₂ --CH₂ --, wherein R₁ has theindicated meaning.
 4. A process according to claim 3, wherein the silverligand is a phosphine of the formula ##STR42## wherein W₁ and X₁ are asdefined in claim 1 and Y₃ is ##STR43## wherein M.sup.⊕ is a cation andX₁ and Y₃ together can be --CH₂ --CH₂ --NR₁ --CH₂ --CH₂ --, wherein R₁has the indicated meaning.
 5. A method according to claim 4, wherein thesilver ligand is a phosphine of the formula ##STR44## wherein Y₃ is asdefined in claim 6, W₂ is --CH₂ --CH₂ --CN, ##STR45## wherein each of R₁and R₂ independently is a hydrogen atom or an alkyl group of 1 to 4carbon atoms, alkyl is an alkylene group of 1 to 4 carbon atoms, n is aninteger from 1 to 5, M.sup.⊕ is a cation and halogen is in particular achlorine or bromine atom, and X₂ and Y₃ together can be --CH₂ --CH₂--NR₁ --CH₂ --CH₂ --, wherein R₁ has the indicated meaning.
 6. A methodaccording to claim 5, wherein the silver ligand is a phosphine of theformula ##STR46## wherein Y₃ is as defined in claim 6, W₃ is --CH₂ --CH₂--CN or ##STR47## wherein M.sup.⊕ is a cation, U is an alkyl group of 1to 4 carbon atoms, n₁ is a integer from 2 or 3 and k is an integer from2 to 4, R₁ and R₂ are as defined in claim 7 and X₃ and Y₃ together canbe --(CH₂)₂ --N(CH₃)(CH₂)₂ --.
 7. A method according to claim 6, whereinthe silver ligand is a phosphine of the formula ##STR48## wherein W₃ andY₃ are as defined in claim 6 and X₄ is ##STR49## wherein M.sup.⊕ is acation and X₄ and Y₃ together can be --(CH₂)₂ --N(CH₃)--(CH₂)₂ --.
 8. Amethod according to claim 7, wherein the silver ligand is a phosphine ofthe formula ##STR50## wherein W₃ is as defined in claim 6, Y₄ is--(CH₂)₂ --SO₃ .sup.⊖ M.sup.⊕, --(CH₂)₃ --SO₃ .sup.⊖ M.sup.⊕, --(CH₂)₄--SO₃ .sup.⊖ M .sup.⊕, --CH₂ N(C₂ H₅)₂ or --(CH₂)₂ --OCH₃, X₅ --CH₂--CH₂ --CN or --(CH₂)₂ --OCH₃ and M.sup.⊕ is a cation and X₅ and Y₄together can be --(CH₂)₂ --N(CH₃)(CH₂)₂ --.
 9. A method according toclaim 1, wherein a preparation which contains(a) a strong acid, (b) awater-soluble iodide, (c) a dye bleach catalyst in an amount of 0.5 to 5g/l, (d) an organic water-soluble oxidant, (e) an antioxidant, and (f) awater-soluble tertiary phosphine,is used for the silver bleaching (3),optionally combined with the dye bleaching (2).
 10. A method accordingto claim 1, wherein a bleach-fixing preparation which contains(a) astrong acid, (b) an organic water-soluble oxidant, (c) one or more ofthe ligands: thiocyanide, chloride, bromide, iodide and thiourea, (d)optionally a dye bleach catalyst, and (e) a water-soluble tertiaryphosphine,is used for the silver bleaching (3) combined with the fixing(4).
 11. A method according to claim 1, wherein a preparation whichcontains(a) a strong acid, (b) a water-soluble organic oxidant, (c) acatalyst, (d) optionally a water-soluble iodide, and (e) a water-solubletertiary phosphine,is used for simultaneously carrying out the processsteps dye bleaching (2), silver bleaching (3) and fixing (4).
 12. Amethod according to claim 1, in which a photographic material is usedwhich contains, in each of at least two layers, a dye which can bebleached imagewise and whose absorption maximum corresponds to one ofthe primary colours red, green and blue, with a silver halide emulsionlayer sensitive to a particular spectral region being assigned to eachdye, and in this material,(a) a silver halide emulsion layer consistingat least partially of silver iodide is assigned to the dye whoseundesired parasitic colour density is to be compensated, (b) in afurther layer, at least a second dye whose main colour densitycorresponds to a parasitic colour density, requiring compensation, ofthe first dye and a silver halide emulsion which contains no iodide ionsare present, (c) a further layer, which is adjacent to the layercontaining the second dye, contains colloidal nuclei which are capableof depositing metallic silver from soluble silver complexes, (d) aseparating layer is present between the layer containing the nuclei andthe dye layer the parasitic colour density of which is to becompensated, and the silver developing bath with which the material istreated contains a ligand which is able to produce water-soluble silvercomplexes which are capable of diffusion, wherein at least oneprocessing bath contains water-soluble tertiary phosphine.
 13. A processof claim 8 wherein the silver ligand is a phosphine of the formula##STR51##
 14. Preparation suitable for carrying out the processingmethod according to claim 1, which contains as silver ligand awater-soluble tertiary organic phosphine in solution.